1. Field of the Invention
The present invention relates to a headlamp of a vehicle such as an automobile, and more specifically relates to a vehicular headlamp that increases an illumination effect in front of a traveling host vehicle to help ensure driving safety.
2. Related Art
In order to increase the safety of a traveling host vehicle, it is necessary to brightly illuminate a travel route of the host vehicle (hereinafter also referred to as a host vehicle lane) and improve the visibility of the host vehicle lane. Especially during high speed driving, visibility in the host vehicle lane up to a certain distant area ahead must be increased. In such cases, the illumination from a high-beam distribution pattern, which is capable of illumination over a long distance and has a laterally wide illumination range, is preferred over the illumination from a low-beam distribution pattern. However, a high-beam distribution pattern is prone to dazzling oncoming and preceding vehicles. For this reason, during ordinary driving, illumination must be performed using a low-beam distribution pattern. Thus, ensuring sufficient visibility of the host vehicle lane becomes an issue.
Art has been proposed for increasing the visibility of the host vehicle lane, wherein an illumination direction (illumination optical axis) of a headlamp is controlled so as to deflect rightward, leftward, upward, and downward. According to Patent Document 1, deflecting the illumination direction of the headlamp rightward and leftward so as to follow a steering angle of the automobile increases visibility ahead in the host vehicle lane on a curved road. Also, according to Patent Document 1, deflecting the illumination direction of the headlamp upward when the host vehicle is driving at high speed illuminates a long distance in front of the host vehicle and increases the visibility of the host vehicle lane, even if the low-beam distribution pattern is still used.
[Patent Document 1] U.S. Pat. No. 6,848,814